This is a graph of climate data provided by the Bureau of Meteorology for Sydney’s Observatory hill weather station from 1859 up until the present.

There’s some interesting trends here. The monthly means fluctuate so much it’s difficult to see a pattern. But when you start to look at the longer term averages, 1 year, 5 years, 10 years and more there is a clear warming trend, but there’s also a lot of fluctuations, sometimes over periods as long as 10 years.

More long term weather data from the BOM. Rainfall doesn’t seem to have a long term trend like temperature and sea level. Although in the medium term it matches temperature and sea level with the El Niño - La Niña cycle.

Rainfall data is taken from the same 2 Observatory Hill weather stations as temperature and covers from Jan 1858 to May 2025

The chart is interactive, so have a play by selecting the data sets you want to see.

The BOM maintains historical tidal measurements for Sydney going back to 1914. The data was tougher to find than for temperature but it’s just as interesting. Graphing tidal averages over time highlights long and short term trends in sea level. Like temperature it gets more interesting when looking at the longer term averages, there are trends of rising and falling sea level lasting 10 years or more, but the clear long term trend is up.